Hi all (from Vienna :)), I've been working on some evolutions of the AEAG "Mask" plugin. This plugin allows to define a "stencil" layer on top of other layers. The idea is to be able to highlight a part of the canvas by hiding (completely or with some transparency) the other parts. And it has to work when the atlas rendering is turned on, adapting the current geometry to the atlas geometry. A first step to integrate this into the core was to add a new "exterior" filling mode. I've sent a pull request and the merging process is on its way. https://github.com/qgis/QGIS/pull/1254
There is still some tricky issues to overcome if we want to have something properly integrated. One of the remaining issues is related to labeling, because we want to be able to also hide labels from "masked" parts, or to display them "below" the mask layer (in case of transparency). There is some partial solution to that using kinds of hacks. For instance, labeling expressions may be used for that, something like "CASE WHEN contains($mask_geometry, $geometry) THEN ... ELSE '' END" or using the 'show' data defined labeling field. But this has some limitations : it is not very user-friendly, and the spatial predicates must be choosen wisely, especially when on-the-fly simplifications are enabled. So ... I was thinking of something more integrated. And it might imply to enhance a little bit the labeling engine. I was thinking of : - adding something like a label layer with a 'Z' ordering that the user could place with drag and drop in the rendering 'stack'. I am not sure yet of the technical details, and PAL possibilities or limitations here, but there is apparently ways to define 'obstacles' objects for the labeling engine. So labels from a layer would be placed with label boxes from the layers below considered as obstacles. - exterior fills would also be considered as obstacles (if they are opaques) - label layer rendering would be mixed with vector layer rendering, so rendering options avaiable to vector layers could be also used on label layers (blending modes and so on). Are there some interests for that ? Can you see other ways to do ? -- Hugo Mercier Oslandia _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
